Breast Milk Storage Guidelines: How long can breastmilk stay out?

Breast milk is a rich source of nutrients and should be treated with care. It’s essential to follow proper storage guidelines for fresh breast milk to ensure you’re feeding your baby the best possible nutrients during this critical time in their development.

The problem is that many moms don’t know how long they can keep breastmilk out at room temperature before it goes bad. I was one of those moms when I first became a mother. When I started using a breast pump and power pumping to build my supply, I knew I needed to find out how to store it.

As a new mom, I was constantly worried about how long my breastmilk would last. I didn’t want to waste any of it, so I did some research online. According to most websites, breastmilk can stay at room temperature for up to four hours. But what if I’m not going to use it all within that time? Can I freeze it and then thaw it later?

I wasn’t sure what the answer was, so I asked my friends. Some said you could freeze breastmilk after it had been thawed, while others said you couldn’t. I was getting so confused!

Finally, I decided to do my research and called the experts: the lactation consultants and nurses at my local hospital. Now I am sharing all I learned with you. This article will give you helpful tips and information about storing, freezing, and thawing breast milk.

Breast Milk Storage

Here’s what we found:

  • You can store breastmilk at room temperature for up to four hours.
  • After four hours, breastmilk needs to be refrigerated.
  • You can keep it in the fridge for up to four days.
  • If you want to freeze breastmilk, it can be stored in the freezer for up to six months.
  • You can keep thawed breastmilk in the fridge or in a cooler with ice packs for up to 24 hours.
breastmilk storage

Guidelines for Using Expressed Breastmilk

First, a little information about breastmilk: breastmilk is made of sugars, proteins, fats, vitamins, and minerals. Breast milk provides all the nourishment that a newborn baby needs after their initial amniotic fluid. It contains many necessary nutrients like water, lactose, fat, protein, minerals, and vitamins C, B12, B6, and folic acid.

Many necessary immunities are also passed from mother to baby through breastmilk. Studies have shown that babies exclusively breastfed for the first six months have a lower risk of developing allergies, asthma, and other chronic illnesses.

Breastmilk has many benefits, but it is essential to remember that it is a perishable food item. Bacteria can grow on expressed breastmilk very quickly, so it’s important to follow storage guidelines carefully. Proper washing of pump parts is also important to avoid bacteria growth.

How long does breast milk last at room temperature?

how long can breast milk stay out

Whether you are expressing breast milk with a Haakaa or using a breast pump, the first thing you need to know is that fresh breast milk has a limited shelf life. It’s best to use it within 4-6 hours of pumping. Breast milk can stay at room temperature for up to 4-6 hours if it is freshly expressed milk. After that, it needs to be refrigerated.

How long can breastmilk stay in the fridge?

If you’re not going to use your expressed breast milk right away, you can store it in the fridge for up to four days.

How long does breast milk last in the freezer?

If you want to freeze breast milk, it can be stored in the freezer for up to six months, although it is okay for twelve months in a deep freezer. When freezing breast milk, it’s essential to use a freezer-safe container. You can use unique bags made to store breast milk. Be sure to label the milk with the date you pumped it and the expiration date.

Thawing and Heating Breast Milk

Just like it is crucial to store breast milk properly, it is essential to warm it correctly. 

Warming From the Fridge

To warm refrigerated breast milk, put the milk container in a bowl of warm water. You can also use a bottle warmer designed explicitly for warming breast milk.

Warming From the Freezer

To thaw frozen breastmilk, place the milk container in the refrigerator overnight. In the morning, you can warm it using one of the above methods.

Don’t ever microwave or boil breastmilk! Microwaving breast milk can destroy essential nutrients and immunities. Once the milk has been thawed, you should use it within 24 hours or 48 hours if you keep it in a cooler with ice packs.

It is best to thaw frozen breast milk in the fridge overnight. However, if that is not possible, you can also thaw it by placing the frozen milk in a bowl of warm water. You can also thaw previously frozen milk by holding the bag under warm running water.

Breast Milk Storage Containers

You can store breast milk in the bottles or bags you pumped it directly into. If you plan to freeze your breast milk, it’s best to use special breastmilk bags or bottles designed for freezing milk. These containers have a lower risk of breaking and are less likely to cause bacteria growth.

Remember to label all containers with the date and type of milk (fresh, refrigerated, or frozen) to avoid confusion later. And don’t forget to throw away any expired milk!

What do you do with Leftover Milk?

If you have more expressed breast milk than your baby will drink, you can freeze the leftovers. The best time to store expressed breast milk is shortly after you pump. You can freeze breast milk in bags or bottles.

Unfinished Bottle of Fresh Milk

If your baby doesn’t finish a bottle, the remaining breast milk can be refrigerated for up to two hours and used later. After 2 hours, you should discard the leftover breast milk.

Thawed Milk

When you thaw breast milk, it needs to be used within 24 hours. Once warmed or brought to room temperature, you should use it within two hours. You should never refreeze thawed breast milk.

Breast Milk Do’s and Don’ts


  • leave room in the bag when freezing since breast milk expands
  • wash hands before handling breast milk
  • use a sterile glass of food-grade plastic bottles that are BPA-free when storing breastmilk
  • use storage bags made to store human milk
  • talk to your doctor if you are concerned about the color of your stored milk
  • freeze milk if you won’t use it within 24 hours
  • Date and label milk before storing it


  • store milk in the freezer door instead place it in the back where it is coldest
  • store in large quantities, instead store in increments of 4-6 ozs
  • be alarmed if stored milk separates into a cream layer and a milk layer
  • shake milk; instead, swirl gently to mix
  • microwave breast milk can destroy proteins and nutrients and create hot spots
  • add warm milk to cooled or frozen milk, cool freshly expressed milk before adding to other cooled milk
  • use disposable bottle liners for storing human milk

FAQs for Storing Breastmilk

1. How to tell if you shouldn’t use stored breast milk?

A few signs can indicate that breast milk has gone bad. If the milk has an off odor, is discolored, or if it contains chunks or lumps, it should be discarded. Additionally, if the milk has been stored at room temperature for more than four hours, or if it has been in the fridge for more than seven days, you should not use it.

2. What is the best way to store breast milk while traveling?

When traveling with expressed breast milk, it’s important to keep it cool. An insulated breastmilk cooler bag with ice packs is an excellent option for storing milk while on the go. If you’re traveling by car, keep the cooler in the air-conditioned part of the vehicle and out of direct sunlight. If you’re flying, pack the cooler with ice packs or frozen gel packs, and store it in a carry-on bag. Be sure to refrigerate milk once you reach your destination.

3. Can I put breast milk back in the fridge after baby drinks from it?

Yes, you can put breast milk back in the fridge after the baby drinks from it. Make sure to use the leftover milk within 2 hours. However, you should discard any milk left at room temperature for more than four hours.

4. Can warmed milk be refrigerated again? 

No! Warmed milk cannot be refrigerated again. The reason is that the proteins in milk become denatured when you heat it, and they can’t go back to the way they were. Additionally, bacteria can grow more quickly in milk that has been warmed up. So, if you have milk that has been warmed and then cooled, you should use it within 2 hours.

5. Can you let refrigerated milk come to room temperature?

Yes, you can let refrigerated milk come to room temperature. Sometimes your baby may prefer that to have it heated up. Giving room temperature milk or cold milk is acceptable for your baby. However, you should discard any milk left for more than 4 hours at room temperature.

6. Can you reheat breastmilk more than once?

It is not usually recommended to reheat milk more than once because the proteins in milk can become denatured after heating, and eating warm or cooled milk may not be as beneficial for your baby. 

7. Is it okay to freeze breastmilk for a later date?

Yes! Freezing breastmilk is a great way to store it for later use. It is best to freeze as soon as you know you will not use the milk within 24 hours.

breast milk in storage bags

8. Can you store breast milk from the same day together?

Yes, you can store breast milk from the same day together as long as it is in a sterile container and labeled with the date. It’s best to keep milk in smaller increments to be used within a few days.

However, thoroughly cool the freshly expressed breast milk in the refrigerator or a cooler before adding it to previously chilled or frozen milk.


So, now you know how long breastmilk can stay out and the proper way to store it. Breast milk is an essential source of nutrition for your baby, so be sure to take care of it! By following these simple tips, you can ensure that your stored breast milk remains safe and nutritious for your little one.

Some key points to remember about breastmilk storage:

  • Make sure to label breast milk storage bags with the date and time pumped
  • You can store milk in the fridge for up to four days
  • Do not store breast milk in the freezer for more than six months unless in a deep freeze, then up to 12 months
  • When thawing breast milk, be sure to use it within 24 hours
  • Never refreeze breast milk

As you can see, it’s essential to follow proper storage guidelines for breastmilk. You can ensure your baby is getting the best possible nutrients during this critical time in your baby’s health.

Breast Milk Storage Guidelines: How long can breastmilk stay out?